Inequivalence of difference sets: on a remark of Baumert
The electronic journal of combinatorics, Tome 20 (2013) no. 1
An often cited statement of Baumert in his book Cyclic difference sets asserts that four well known families of cyclic $(4t-1,2t-1,t-1)$ difference sets are inequivalent, apart from a small number of exceptions with $t< 8$. We are not aware of a proof of this statement in the literature.Three of the families discussed by Baumert have analogous constructions in non-cyclic groups. We extend his inequivalence statement to a general inequivalence result, for which we provide a complete and self-contained proof. We preface our proof with a survey of the four families of difference sets, since there seems to be some confusion in the literature between the cyclic and non-cyclic cases.
DOI :
10.37236/2277
Classification :
05B10, 05B20
Mots-clés : difference sets, Hadamard matrices
Mots-clés : difference sets, Hadamard matrices
Affiliations des auteurs :
Padraig Ó Catháin  1
@article{10_37236_2277,
author = {Padraig \'O Cath\'ain},
title = {Inequivalence of difference sets: on a remark of {Baumert}},
journal = {The electronic journal of combinatorics},
year = {2013},
volume = {20},
number = {1},
doi = {10.37236/2277},
zbl = {1267.05048},
url = {http://geodesic.mathdoc.fr/articles/10.37236/2277/}
}
Padraig Ó Catháin. Inequivalence of difference sets: on a remark of Baumert. The electronic journal of combinatorics, Tome 20 (2013) no. 1. doi: 10.37236/2277
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